Optimum Battery set up for my EV scoot Spec?

jdevane5 said:
....27S25P....
I will use 18650's Samsung 30Q, 3000 mAh, 3.6v, Discharge 15A...
Click to expand...
From the OPs text.

25Px15A Discharge
But Samsung has listed 20A in the datasheet. So no need to worry while acceleration.
 
Ah, I thought you meant 375 cells.

Either way, the OP should understand that the number of cells in series gives the total voltage (27S @ 4.2V = 113.4V) and the number of parallel cell groups (27 cells in series) gives the maximum amps (25P @ 15A = 375A, 25P @ 20A = 500A). And that a 27S25P battery pack would mean 27x25=675 cells in total.
 
SlowCo said:
Ah, I thought you meant 375 cells.

Either way, the OP should understand that the number of cells in series gives the total voltage (27S @ 4.2V = 113.4V) and the number of parallel cell groups (27 cells in series) gives the maximum amps (25P @ 15A = 375A, 25P @ 20A = 500A). And that a 27S25P battery pack would mean 27x25=675 cells in total.
Click to expand...

Big thanks -675 is the one.
I just watched an excellent You tube video on battery building by Lee Wright and realised I had screwed up on the battery count!
 
So finally got around to sorting my battery for my ev Lambretta...

Going with 21700's,not a bad price.

23S10P.
Ordering 235 batteries ,so got the weight of the B.pack to around 20kg with all the non battery kit, nickel strip, packaging etc.
Ordered 5 spare batteries.

Should see my motor delivery this week, QS hub motor 12kw 70H V4. 96v. Looks to be about 10kg.
Fairdriver controller ND961200,from info I have found it sounds to be around 3kg.

Lambretta engine removed was 38kg.

Need to design a swing arm which I will likely make out of 6061 T6 billet.

Looking forward to building now. Just need to sort the donor scoot out and check the frame, reweld where needed etc.
 
SlowCo said:
Then program the controllers max. battery amps to 450A. Better even max. 400A to help the battery pack last longer.
Click to expand...

So I'm starting to get a rough idea on a range for my build..but could do with help on the range calc..

My setup 23S10P 96V set up;

So using cell max at 4.2v(nominal 3.6v), 2400mAh,
4.2 x 10 = 42...96V x 42 = 4,032 Wh, what's a good Watts per mile to use, with drag, weight etc?

I was thinking around 100Wh,if so that puts me approx. 40 mile range on the pack.

Am I way off on expected Range?? And are my calcs OK?
 
jdevane5 said:
My setup 23S10P 96V set up;

So using cell max at 4.2v(nominal 3.6v), 2400mAh,

4.2 x 10 = 42...96V x 42 = 4,032 Wh,
Click to expand...

10p x 2.4Ah per cell is 24Ah, total pack capacity.

23s * 3.6v nominal is 82.8v nominal pack voltage
23s * 4.2v max is 96.6v max pack voltage

24Ah * 82.8v = 1987.2Wh nominal
24Ah * 96.6v = 2318.4Wh max (but you should use the nominal rating)

So you have a 2kWh pack assuming you get that 2.4Ah/cell actual capacity.

(if the cell rated capacity is based on a deep discharge under ideal conditions at a low C-rate, and your pack isn't being discharged that far and/or is under less ideal conditions at a high C-rate, you will get less capacity)


what's a good Watts per mile to use, with drag, weight etc?
I was thinking around 100Wh,if so that puts me approx. 40 mile range on the pack.
Click to expand...

Wh/mile is primarily speed dependent, as well as terrain, wind, weight, etc. See my post on the previous page of this thread:
https://endless-sphere.com/forums/viewtopic.php?f=10&t=114216#p1688901

But if you assume 100wh/mile, then you get about 20 miles with a 2kWh pack. If you need 40 miles at that power consumption level, then you need a 23s 20p pack of these cells.
 
amberwolf said:
jdevane5 said:
My setup 23S10P 96V set up;

So using cell max at 4.2v(nominal 3.6v), 2400mAh,

4.2 x 10 = 42...96V x 42 = 4,032 Wh,
Click to expand...

10p x 2.4Ah per cell is 24Ah, total pack capacity.

23s * 3.6v nominal is 82.8v nominal pack voltage
23s * 4.2v max is 96.6v max pack voltage

24Ah * 82.8v = 1987.2Wh nominal
24Ah * 96.6v = 2318.4Wh max (but you should use the nominal rating)

So you have a 2kWh pack assuming you get that 2.4Ah/cell actual capacity.

(if the cell rated capacity is based on a deep discharge under ideal conditions at a low C-rate, and your pack isn't being discharged that far and/or is under less ideal conditions at a high C-rate, you will get less capacity)


what's a good Watts per mile to use, with drag, weight etc?
I was thinking around 100Wh,if so that puts me approx. 40 mile range on the pack.
Click to expand...

Wh/mile is primarily speed dependent, as well as terrain, wind, weight, etc. See my post on the previous page of this thread:
https://endless-sphere.com/forums/viewtopic.php?f=10&t=114216#p1688901

But if you assume 100wh/mile, then you get about 20 miles with a 2kWh pack. If you need 40 miles at that power consumption level, then you need a 23s 20p pack of these cells.
Click to expand...

Hey thanks for all this, excellent explanation and thanks for the reminder on the previous range thread.
The exact reason I joined this forum.

There are so many variables to calculating range, however I think I will up the battery pack a bit -but is it not a balance now as the pack gets larger in P what the controller can handle? I have a Fairdriver ND961200 and a 10kw 96v hub motor.
With that I need to also check package space...a 23S20P battery is considerably larger and heavier..
 
If you have room to enlarge your battery pack by adding more cells in parallel it is only a good thing. That way you will be able to use the controller and motor to their full potential and not pull too much amps from the battery. The range is mostly dependent on how you ride but more cells in parallel also means more Ah and thus more range on average.
 
jdevane5 said:
however I think I will up the battery pack a bit -but is it not a balance now as the pack gets larger in P what the controller can handle? I have a Fairdriver ND961200 and a 10kw 96v hub motor.
Click to expand...
Not sure what you mean by "what the controller can handle"? The controller draws whatever current it needs, it doesn't matter if the battery pack can output say, a thousand times what the controller uses--that just means the battery would never be under stress. ;)

Voltage, that would matter--if the pack voltage is higher than controller can do, then you get smoke. :oops:

battery Ah, Wh, Amps, Watts, capabilities don't harm the controller if they're higher than controller needs.


If your controller "961200" means 96v 1200w, then that means the controller probably can max draw 1200 / 96 = 12.5A. If the 1200 is amps rather than watts, then that means it can draw 1200A max, so your pack has to be able to sustain that for as long as you ever might draw that much, so you also have to have enough parallel cells to do that without putting a strain on the cells (so not running them near their max C-rate), to extend their lifespan. (the harder you push cells, the shorter lifespan you get).

Anyway...what I meant to say was that if the controller can draw 1200A max, and you have a pack capable of supplying say, 4000A, it just means the pack will never be strained by the controller.

If you had a controller that can draw 1200A max, and your pack can only supply 1000A, then you have a potential problem with the pack being strained during max draw by the controller.

In neither case would the controller itself be strained by the pack. ;)


With that I need to also check package space...a 23S20P battery is considerably larger and heavier..
Click to expand...
Yes, it will be twice the size and weight of the 23s10p pack because it has twice as many cells and holders, etc.
 
j bjork said:
The 1200 is phase amps, battery amps is maybe half of that according to specs.( I haven't looked now, only from memory)
I think something like 28s 20p would be more suitable. Why a 96V controller and limit to something more suitable for the 84V?
Click to expand...

I went with the 96V controller based on what I had read on Fairdriver unit and it made sense given motor is 96V.
Are you saying I could go with a 84V controller for the 96V motor -Would that not restrict full potential of the motor?
The Fairdriver Controller is 1200A Phase, 600A Line current.

And why is 28s20p more suitable?

And Apologies for all the questions, I'm finding my way on ev builds :0)
 
Search for the difference between nominal and maximum voltage. Nominal cell voltage is between 3.6V and 3.7V where maximum cell voltage is 4.2V.
Now calculate the nominal and maximum voltage for a 23S and a 28S battery pack and look up the maximum voltage of your controller :wink:
(23S is very low and 28S is too much)
 
SlowCo said:
Search for the difference between nominal and maximum voltage. Nominal cell voltage is between 3.6V and 3.7V where maximum cell voltage is 4.2V.
Now calculate the nominal and maximum voltage for a 23S and a 28S battery pack and look up the maximum voltage of your controller :wink:
(23S is very low and 28S is too much)
Click to expand...

So looks like 27S is the winner, max controller V = 115V.
I might go with 27S30P -Got to check battery package in my design though.
 
Had some quotes for a battery from Li-Tech ahead of me potentially building a battery myself.

Went with 27S20P using and LG 5000mAh, 3.6V -which came in at approx $3000
LG Chem Lithium Ion INR21700 M50T 18.2Wh

I asked for the detailed Spec of the Cell (below_ and it looks to have a very low C rating at .3 :?

So will likely go with the Molicel 42A cell I found and build a 27S30P battery pack ,which will meet my project needs.

LG Chem Lithium Ion INR21700 M50T 18.2Wh Spec
Nominal Specification

2.1 Energy By Std. Charge / Discharge Nominal 18.2Wh
Minimum 17.6Wh
2.2 Nominal Voltage Average by Std. Charge / Discharge 3.63V
2.3 Nominal Shipping SOC - Below 30%
2.4 Standard Charge Constant current 0.3C (1,455mA)
Constant voltage 4.2V
End current(Cut off) 50mA

2.5 Max. Charge Voltage In all measurements and operations of the
cell, the minimum closed circuit voltage
allowable shall not be over the following
value
4.20V
2.6 Over Voltage Protection Cell voltage should not go over the
following value to prevent any safety
events. And cell performance can’t be
guaranteed between 4.20V and 4.25V
4.25V
2.7 Min. Discharge Voltage In all measurements and operations of the
cell, the minimum closed circuit voltage
allowable shall not be below the following
 
Dui said:
jdevane5 said:
I need 96V in series and then a given amount of Ah in parallel to gain my range, so its all about how many nmc pouches of cells I can squeeze into my scoot package space and at the same time balancing weight and adequate cooling...

Am I on the right track, or completely left field?
Click to expand...

Yeah, pretty much. It's a bit simplified but the idea is there.
One other thing to understand is that a given amount of Ah in parallel will also give you the maximum dischage capacity of your pack. In your case, you need it to deliver at the very least 600A, which is called current discharge. There are several ways to determine wether or not your pack will be able to provide this kind of current, but in order to know that you need to know at least the following information:
-How many cells are in parallel?
-Cell individual capacity?
-Individual cell maximum current OR Discharge rate (or C-Rate) of each cell (some manufacturers will provide max currents, some other manufacturers will provide the C-rating

Lets say you have 10 cells in parallel, each of these having a maximum discharge current of 30 amps. Then 10*30= 300, your battery can deliver a maximum of 300A. Too small, you'll need at least 20 cells in parallel to match your need.

Lets now say that you have 25 cells in parallel, individual cell capacity is 1200mAh and the maximum C rating is 3C. So, 25 x 1.2 x 3 = 90 Amps. So here you'll need around 7 times more cells to reach 600A.

I recommend you to start designing your battery with these simple calculations in mind first. Current draw is what ultimately kills batteries and lowers performance, so you need the battery to at the very least match the current your controller will draw. Otherwise the voltage will sag, the battery will heat and get damaged quickly.

That means, check for a battery with the best possible discharge current, or with a very large capacity.
600A is a lot of current, not many batteries are able to deliver that without breaking a sweat. You say that space isn't an issue, but on scooters it usually is, together with weight. That is especially true if you want to get a very long range at the same time (100miles on one charge is quite a lot).

Hope this helps a little.
Click to expand...

So I continue to look at Battery options, either build myself or get a battery built.
One question I have is on the statement above about requiring a max discharge capacity of at least 600A -Where did you get this from?

From looking at my motor Spec, it states peak battery current at 130A & suggested phase current at 587-734A.
The controller max current draw is 600A but my assumption is I could restrict this and would need to anyway based on my motor Spec? I know this would not get the max performance but I'm trying to balance the battery with the motor and controller.

So what would be the minimum current capacity for my battery?
 
jdevane5 said:
From looking at my motor Spec, it states peak battery current at 130A & suggested phase current at 587-734A.
The controller max current draw is 600A but my assumption is I could restrict this and would need to anyway based on my motor Spec? I know this would not get the max performance but I'm trying to balance the battery with the motor and controller.

So what would be the minimum current capacity for my battery?
Click to expand...

In your first post you write that you have a QS 260 70H hub motor. That should be able to take a much higher peak amp input than 130A. I think the guys that are pushing the QS 205 50H to it's limits use even more than 130A. And that's a much smaller and slimmer motor.
 
jdevane5 said:
So I continue to look at Battery options, either build myself or get a battery built.
One question I have is on the statement above about requiring a max discharge capacity of at least 600A -Where did you get this from?
Click to expand...


Well I got it from you actually, you said you'llbe using a "Fairdriver controller ND961200 Phase 1200A, 600a line current". :wink:
Based on what I've seen in real life the Nanjing Far Drives actually does deliver and consume that much current. What you call "line current" is the current your controller will ask from the battery. Here, 600Amps.

jdevane5 said:
From looking at my motor Spec, it states peak battery current at 130A & suggested phase current at 587-734A.
Click to expand...


You have one of the most powerful motor QS makes in this size. Don't ask me why because it's also a mystery to me, but for some reason QS power ratings are wildly inaccurate and those motors can actually take some crazy beating far beyond whatever is written on their covers.
To give you an example, my current scooter has a 10 inches QS WP20030X, so that's rated at 2000W by QS. I'm using a sabvoton at 210A battery and 510A/phase. The little 2000W motor deals brilliantly with 500+ amps everyday :wink:
I'm fairly confident your motor will be ok even at full power even though 1200 amps sound really crazy. I'm not sure however that so much power is wise on a scooter, to be honest I'd be scared, that would be three times the power of my machine which isn't exactly slow... :shock:
I'm not sure you imagine how much powerful this can be. Don't forget the brakes, suspensions, tires, frame etc, they'll really need to match otherwise that'll be a death trap.

jdevane5 said:
The controller max current draw is 600A but my assumption is I could restrict this and would need to anyway based on my motor Spec? I know this would not get the max performance but I'm trying to balance the battery with the motor and controller.
Click to expand...


My assumption was that if you were to buy this controller then you'd use it's full power since otherwise it's a bit of a waste, but yes you can program it to limit the battery current, thus protecting the battery.


jdevane5 said:
So what would be the minimum current capacity for my battery?
Click to expand...

The minimum is whatever you want, there's no minimum since you have a programmable controller. It all depends on what you can afford.
It's not impossible to find a battery capable of outputing 600Amps, mine does it :wink:
 
Dui said:
jdevane5 said:
So I continue to look at Battery options, either build myself or get a battery built.
One question I have is on the statement above about requiring a max discharge capacity of at least 600A -Where did you get this from?
Click to expand...


Well I got it from you actually, you said you'llbe using a "Fairdriver controller ND961200 Phase 1200A, 600a line current". :wink:
Based on what I've seen in real life the Nanjing Far Drives actually does deliver and consume that much current. What you call "line current" is the current your controller will ask from the battery. Here, 600Amps.

jdevane5 said:
From looking at my motor Spec, it states peak battery current at 130A & suggested phase current at 587-734A.
Click to expand...


You have one of the most powerful motor QS makes in this size. Don't ask me why because it's also a mystery to me, but for some reason QS power ratings are wildly inaccurate and those motors can actually take some crazy beating far beyond whatever is written on their covers.
To give you an example, my current scooter has a 10 inches QS WP20030X, so that's rated at 2000W by QS. I'm using a sabvoton at 210A battery and 510A/phase. The little 2000W motor deals brilliantly with 500+ amps everyday :wink:
I'm fairly confident your motor will be ok even at full power even though 1200 amps sound really crazy. I'm not sure however that so much power is wise on a scooter, to be honest I'd be scared, that would be three times the power of my machine which isn't exactly slow... :shock:
I'm not sure you imagine how much powerful this can be. Don't forget the brakes, suspensions, tires, frame etc, they'll really need to match otherwise that'll be a death trap.

jdevane5 said:
The controller max current draw is 600A but my assumption is I could restrict this and would need to anyway based on my motor Spec? I know this would not get the max performance but I'm trying to balance the battery with the motor and controller.
Click to expand...


My assumption was that if you were to buy this controller then you'd use it's full power since otherwise it's a bit of a waste, but yes you can program it to limit the battery current, thus protecting the battery.


jdevane5 said:
So what would be the minimum current capacity for my battery?
Click to expand...

The minimum is whatever you want, there's no minimum since you have a programmable controller. It all depends on what you can afford.
It's not impossible to find a battery capable of outputing 600Amps, mine does it :wink:
Click to expand...

I've been looking for a decent big battery supplier but cant find anyone yet with a battery output of 600+A.
Budgets not a problem.
Its also a balance of battery mass versus package space available, I plan to put the battery under the frame to get the CofG down.
Reason I got the motor and controller was to allow me to max out the Spec of the Lambretta as much as possible, I race petrol Lambretta's so the mechanical elements are straight forward for me, its the EV set up that's new -But I'm learning.

Given these Motors are way out Spec wise on max performance potential I will aim at as much A as possible in package space now assigned for the battery.
 
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